mitigate unexpected state (#233)

* mitigate unexpected state

remove ClearAllNonces

* use string constant

signer/cosigner_nonce_cache_test.go

@@ -99,7 +99,23 @@ func TestClearNonces(t *testing.T) {
 
 	for _, n := range cnc.cache.cache {
 		require.Len(t, n.Nonces, 2)
+		oneFound := false
+		twoFound := false
+		for _, cnr := range n.Nonces {
+			if cnr.Cosigner == cosigners[1] {
+				oneFound = true
+			}
+			if cnr.Cosigner == cosigners[2] {
+				twoFound = true
+			}
+		}
+		require.True(t, oneFound)
+		require.True(t, twoFound)
 	}
+
+	cnc.ClearNonces(cosigners[1])
+
+	require.Equal(t, 0, cnc.cache.Size())
 }
 
 type mockPruner struct {

signer/local_cosigner.go

@@ -435,6 +435,8 @@ func (cosigner *LocalCosigner) getNonce(
 	return nonce, nil
 }
 
+const errUnexpectedState = "unexpected state, metadata does not exist for U:"
+
 // setNonce stores a nonce provided by another cosigner
 func (cosigner *LocalCosigner) setNonce(uuid uuid.UUID, nonce CosignerNonce) error {
 	// Verify the source signature
@@ -456,7 +458,8 @@ func (cosigner *LocalCosigner) setNonce(uuid uuid.UUID, nonce CosignerNonce) err
 	// generate metadata placeholder
 	if !ok {
 		return fmt.Errorf(
-			"unexpected state, metadata does not exist for U: %s",
+			"%s %s",
+			errUnexpectedState,
 			uuid,
 		)
 	}

signer/threshold_validator.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"strings"
 	"sync"
 	"time"
 
@@ -734,6 +735,10 @@ func (pv *ThresholdValidator) Sign(ctx context.Context, chainID string, block Bl
 						"err", err.Error(),
 					)
 
+					if strings.Contains(err.Error(), errUnexpectedState) {
+						pv.nonceCache.ClearNonces(cosigner)
+					}
+
 					if cosigner.GetID() == pv.myCosigner.GetID() {
 						return err
 					}